Window Selection

Window Selection

Many of the features of DigImage may operate on either the entire buffer or a window defined within a buffer. The basic window is rectangular with pixel resolution. If non-rectangular windows are required, then it will be necessary to set up a mask buffer which can be ANDed with the required image to mask of any unwanted features. Suitable routines for producing such a mask buffer may be found in [C: Contours]. This submenu allows interactive and batch access to the selection of such a window.

The window is restricted to being rectangular with horizontal and vertical boundaries, and may range in size from 1x1 to 512x512 pixels, in steps of one pixel. The window defined on entry will depend on the particular facility in use. It may be the current DigImage default window, the last window utilised by the particular facility being invoked, or some other default. The DigImage default window is a user-definable: it is set to the current window if the G option is chosen to exit the window selection routine. If the Q option is chosen, the default window is unchanged. A number of options exist for defining or modifying the size and shape of the window. If a mouse is installed, then this may also be used for adjusting the size and shape of the window.

The following options move one corner of the window:

<up> Move the top left (bottom right) corner of the window up by the current step amount. To toggle between the top left and bottom right corners, see X below. To set the step size, see S below.

<down> Move the top left (bottom right) corner of the window down by the current step amount.

<left> Move the top left (bottom right) corner of the window to the left by the current step amount.

<right> Move the top left (bottom right) corner of the window to the right by the current step amount.

These options move the window, without changing its size:

page up/page down Move the window to the top/bottom of the buffer.

home/end Move the window to the left/right extremem of the buffer.

1 Move the window to the left and down by the current step amount.

4 Move the window to the left by the current step amount.

7 Move the window to the left and up by the current step amount.

8 Move the window up by the current step amount.

9 Move the window to the right and up by the current step amount.

6 Move the window to the right by the current step amount.

3 Move the window to the right and down by the current step amount.

2 Move the window down by the current step amount.

C Reduce size of window without changing the position of the window centre.

E Increase size of window wihtout changing the position of the window centre.

X Toggle between opposite corners for use with the cursor keys (<up><down><right><left>).

S Toggle between movement speeds (1 or 16 pixels at a time).

D Set to current default window.

W Set to whole screen.

M Enter coordinates from keyboard. Coordinates for the top left and bottom right of the window may be entered manually as either pixel or world coordinates.

T Toggle mask. Toggles through a range of optional masks for indicating the window boundary.

V Enable mouse <=> no VTR control. This option will disable the VTR control (if currently active), allowing the use of a serial mouse, if such a mouse is fitted.

MOUSE - Available only if Video routines are not enabled:

    Left button        - Drag top left corner; do not shift bottom right
    Middle button      - Drag top left corner (and bottom right), keeping
                         centre of window where it is
    Right button       - Drag bottom right corner; do not shift top left
    Left+Right buttons - Drag whole window; do not change size or shape
    Left+Middle+Right  - Exit; leave the default window unchanged

G Exit and make this the default window.

Q Exit; leave the default window unchanged


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DigImage User Documentation


Stuart Dalziel, last page update: 19 February 1996